Builder Pattern Demo

package BuilderPatternDemo;
// Product
class Car {
    private String engine;
    private String wheels;
    private String color;

    public void setEngine(String engine) {
        this.engine = engine;
    }

    public void setWheels(String wheels) {
        this.wheels = wheels;
    }

    public void setColor(String color) {
        this.color = color;
    }

    @Override
    public String toString() {
        return "Car:\n\tEngine: " + engine + "\n\tWheels: " + wheels + "\n\tColor: " + color + "\n";

    }
}

package BuilderPatternDemo;

// Builder
interface CarBuilder {
    void setEngine(String engine);
    void setWheels(String wheels);
    void setColor(String color);
    Car getResult();
}

package BuilderPatternDemo;

// ConcreteBuilder
class CarBuilderImpl implements CarBuilder {
    private Car car;

    CarBuilderImpl() {
        this.car = new Car();
    }

    public void setEngine(String engine) {
        car.setEngine(engine);
    }

    public void setWheels(String wheels) {
        car.setWheels(wheels);
    }

    public void setColor(String color) {
        car.setColor(color);
    }

    public Car getResult() {
        return car;
    }


}

In this example, Car is the complex object (the product) that we are trying to build. The CarBuilder interface defines the steps that are necessary to build a car, and CarBuilderImpl (the concrete builder) implements these steps. CarDirector (the director) uses the CarBuilder to create a car. This allows us to construct a Car object step-by-step, and the construction process can be different for different types of cars.